The Acer seems to be the better buy between the two mainly on account of its Blu-Ray drive (BD). There's probably very little else between the two, although the Acer's Core 2 Duo CPU would have a slight edge I suspect. And so would its better HD3470 graphics over the HP's HD3450.
The Acer's also £450 at ttp://click here - i.e. £50 less compared to your Currys link. But study the specs carefully as there are a few variations of the 5920G. G
P.S. If you go for the HP from Scan, get free delivery - here's how click here or click here